Dynamo-electric machine.



B. e., LAMMB. DYNAMO ELECTRIC MACHINE. APPLICATION FILED JUNE 2 Patented Jan.25, 1910.

, Big. I.

WITNESSES 1.

&z 49% ATT'ORNEY UNITED STATES PATENT onnion BENJAMIN G. 1. mm; F PITTSBURG, PENNSYL ANIA, ASSIGNOR. To wEs'rfNGfioiIsE ELECTRIC & MANUFACTURINGCOMPANY. A CORPORATION or PENNSYLVANIA.

fi YNAIiEO-ELECTRIC MACHINE.

fipecification of Letters Patent. Patented J an. 25, 1910.

. Application filed June 2, 1905. Serial N 0. 263,478.

I 'of Pittsburg, in the county of Allegheny and specifi'cation.

State of Pennsylvania, have invented a new and useful Improvement in Dynamo-Eleotric Machines, of which the following is a My invention .relates to dynamo-electric machines, and it has for its object to provide an improved form of core structure for such machines.

In order to prevent or reduce sparking between the commutator brushes and segments of a dynamo-electric machine, it has become a well known practice to employ-high-resistance conductors between the armature coils and the commutator segments and to locate such resistance conductors either in the bot toms of the slots that contain the armature coils or in separate slots provided for that purpose. If the resistanceconductors are placed in the bottoms of the slots that con tain the conductors of the-armature winding, additional depth must be provided to ac oommodate them, and if the slots are made of the same width from top to bottom, as is usually done, the'cross-section of the comet. thebases of the teeth that are formed by the slots may be less than is required for the most satisfactory conditions of operation. Experiments have proved that, with a given core and magnetizing winding, the amount of alternating current required to produce a certain flux density inthe core is greater than the amount of direct current required for the same result,.and when the core becomes saturated, or nearly so, the alternating magneto-motive force required for a certain flux density may be two or three times as great as that required if direct current were use Since the self-induction of an alternating current, commutator type motor depends largely upon the number of ampere turns required for magnetization, and since it is desirableto reduce the self-induction to the lowest practicable limits, it is important that the number of ampere turns required for magnetization shall be low. If the armature slots are made of the same width from top to bottom, the magnetic flux density at the bases of the teeth maybe much greater than that at the free ends of the teeth and the' number of ampere turns required to produce commutator Se this flux density at the bases of the teeth may be a relatively-large percentage of the total number of ampere turns required for the magnetization of the iron circuit. lt has been found that the limiting conditions in the design of many of such motors lie in the available cross-sectional area of the iron at the bases of the armature teeth. In order to avoid reducing the cross-section of the teeth at their bases to such an amount that the magnetizing ampere turns become excessive, I propose to reduce the width of the portions ofthe slots in 'whiclrthe resistance conductors are located and to increase the depth of the slot proportionately. and also to employ resistance conductors that are fiat and wide, as comparedwith those which are ordinarily employed and as compared with the conductors of the armature coils.

.In the accompanying drawing. Figure l is a longitudinal, cross-sectional View of a part of an armature of a dynamo-electric machine constructed in accordance with my invention. Fig. 2 is a similar View of a modification of the machine shown in Fig. 1, and Fig. 3 is a View, partially in transverse section, through the magnetizable core of the machine shown in Fig. 1, illustrating the shape of the slots and the armature coils and resistance conductors located therein.

Referring first to Figs. 1 and 3, a magnetizablecore 1 is provided with a'winding 2 the terminals 3 of which are connected to tively high resistance conductors 5, the t-er-' minals 3 being located at the opposite end of the armature from the commutator segments 4. As indicated in Fig. 3, the coil 2 comprises a plurality of conductors 6 that are insulated from each other and from the magupper, wide portion 7 of an armature slot ents t by means of rela- ,netizable core 1 and thatare located in an 8. The resistance conductors 5 are located 4 in a deeper narrow portion 9 of the slot 8. It will be'noted' that the width of the base portion. 10 of each tooth '10" that is formed by adjacent slots may be the same or. nearly the same as the outer ortion if theslots 8 are properly formed. date the conductors to the shape of the slots,

the resistance conductors 5. preferably are made thin and wide and the portions 9 of the slots 8 correspondingl deeper as compared with the structure 'w ich is ordinarily employed.

11 order to accommo- 1 the sides of whichare substantially parallel, of low-resistance conductors located side-by Side in the outer portions of the core slots,

of the coil 2 may be locatedat the same end coilsand'resist-ance conductors and the shape "low-resistance conductors located side by their larger faces substantially parallel to 4 2. The combination with an armature core shown in Fi- 2, the resistance conductor 5 is double on'it-self and the end 3' or the armature. as the commutator. 10bviously,'the arrangement of the armature side .in the outer wide ortions of the core slots, and thinner fiat 1igh,- .resistance conductors arranged, side by side acro s the innernarrowiportions of the core 5 ots-with radii passing through the slots in which l they are located.

provided with slots the outer portions of which are wider than the inner portions and and thinner fiat high-resistance conductors arranged side by side across the inner narrow portions of the core slots with their wider faces. parallel to the sides of the slots. l

- slots.

3. The combination with an armature core provided with slots having relatively narrow openings at the circumference of the armature and the outer portions oi which are wider than the inner portions and the sides of which are substantially parallel, of

"low resistance conductors located side by side in the outer wideportions of the 'core' slots, and thinner flatzhigh-resistance conductors arranged side by side across'the in- ,ner narrow portions ofthe core slots with their wider faces parallel to the sides of the at. The combination with an armature core provided with slots the outer portions of which are wider than the inner portions and the sides of which are substantially parallel,

of low-resistance conductors arranged side by side insuperposed groups in the outer wide portions of the core slots, and thinner fiat high-resistance conductors equal in um-s ber to-those in each of said groups arranged side by side across the inner narrow portions of the core slots with their wider faces parallel to the sides of the slots.

In testimony whereof, I have hereunto subscribed my name this 31st day of Hay BENJ. G. LAMME.

W'itnesses ELIZABETH LIVINGS'LONE,

BIRNEY HINES. 

